GB1271383A - A linear voltage controlled phase shifter for triangular waves - Google Patents

Abstract

1,271,383. Phase shift circuits. PROSSER SCIENTIFIC INSTRUMENTS Ltd. 1 May, 1970 [1 May, 1969], No. 22356/69. Heading H3T. A method of phase shifting a triangular waveform comprises adding a rectangular wave to the triangular wave Fig. 2, and folding over the peaks of the waveform Fig. 3. A triangular wave signal generated by an oscillator G T is applied to a square wave generator 3, the resulting square wave being summed with the triangular wave in adder A 3 . The adder output is then fed to a "commutator" circuit which "folds over" the peaks of the composite waveform when these exceed limits of ŒV M set by two reference signals applied to comparators CP 12 , CP 13 . The square wave generator 3 is similar in form to the "commutator" but has only one reference input D, Fig. 4 (not shown). The generator G T , as shown, comprises an integrator A 1 producing a triangular wave output which is fed to a comparator CP to produce the square wave output. The square wave is also fed via limiter D 1 , D 2 and amplifier A 2 to provide the input to integrator A 1 . In a modification Fig. 5A (not shown), the amplifier A 2 is replaced by another "commutator" similar to commutator 3. In further modifications of the generator G T , Figs. 6A, 7 (not shown) to square wave from the comparator is used to control the switches of an inverter which provides the square wave input to the integrator. Commutator.-Comparator CP 12 produces an output which is either positive or negative, depending on the level of the output from A 3 relative to the reference level + V A . In one state of the comparator output S 1 is open, S 2 connects one input of the amplifier A 4 to earth and the output from A 3 is fed via R and A 4 to the output, A 4 giving a gain of - 1. In the other state of the comparator output S 1 is closed and S 2 open to make the gain of A 4 + 1. A similar operation takes place when the output from A 3 passes the reference -V A , comparator CP 13 providing the control for switches S 1 , S 2 .